Method of making friction elements



2 Sheets-Sheet l rvue/YvO/L 3ra/75 G. BRAHS METHOD 0F MAKING FRICTIONELEMENTS May 22, 1951 Filed June 17, 1947 May 22, 1951 G. BRAHS2,553,698

METHOD oF MAKING FRICTION ELEMENTS Filed June 17, 1947 2 sheets-sheet 2Iig. 6'.

Patented May 22, 1951 UNITED vsTATEs PATENT OFFICE METHOD 0F MAKINGFRICTION ELEMENIS Y George Brahs, Hawthorne, N. J.

f Application June 17, 1947, Serial No. 755,137

7 Claims. (01.2154-81) This invention relates to improved methods ofVmaking friction elements such as friction-discs and clutch facings. i ii The invention has among its objects the provision of an improvedmethodof making an improved friction-.disc which is so constructed thatthe reinforcing Velements in its friction face are largelydiscontinuous, whereby the disc surface has very little if any, tendencyto glaze. The friction disc made by the method of the present inventionis also characterized by its substantial regularity of structurethroughoutits mass.

A further object of the invention is the provision of an improved andsimplified method for making friction-discs, whereby less pressure isrequired in the pressing operation, and the amount of labor required forcleaning, repairing, and otherwise maintaining the disc forming molds isgreatly reduced.

These and further objects of the invention will be more clearly apparentin the `following description of preferred embodiments of thefrictiondisc, and of the method of making it, in accordance with theinvention. In the drawings appended hereto which form a part of suchdescription:

Figure 1 is aview in side elevation of a reinforcing element in the formof a rope-like web;

Figure 2 is a similar view of a rope-like web similar to that of Figure1, but having another braided covering thereon;

Figure 3 is a View in plan of the female portion of a mold containing aplurality of annuli formed from the web shown in Figure 2;

Figure 4 is a view in vertical section through such mold part and itscharge, the section being taken along the line IV-IV in Figure 3;

Figure 5 is an enlarged view in plan of a por-- tion of the discresulting from pressing the annuli in such mold;

Figure 6 is a view in plan ofv such pressed disc after impregnation witha bonding and frictiontreatment material; Y

Figure 7 is a View in planof the disc shown in Figure 6 after it hasbeen coated with a second friction-treatment material;

Figure 8 is a view in plan of a finished frictiondisc made in accordancewith the preferred method of the invention;

Figure 9 is a view in vertical section through a mold employed in thepreliminary pressing of an annular element to be employed in the form ofa friction-disc by an alternative method; and

Figure 10 is aview in vertical sectionof a portion ofv a. second mold,`employed in pressingY a plurality of annular elements, of which one 1sshown in Figure A9, together to form a disc.

Referring to the drawings, the various elements going into the making upof a friction-disc in carrying out the preferred method of theinvention, as Well as the apparatus employed in the performance of suchmethod, are shown in Figures 1 to 8, inclusive. In Figures 9 and 10there are indicated portions of other apparatus by which thefriction-disc may be formed in accordance with an alternative method. 'v

In accordance with the invention, there is employed reinforcing materialin the body of the disc, such material being in the form of elongatedstranded rope-like webs, the lengths of which extend generally in theplane of the disc. Such reinforcing webs may take either of the formsshown in Figure 1 or 2. In Figure 2, the ropelike web, indicatedgenerally by the reference character 2, is composed of a core 4, a rstbraided covering layer 6 over such core, and a second braided coveringlayer 8 over layer'6. In Figure l, the structure of the rope-like web,indicated generally at 2 is the same as that of web 2 but for theomission of the second covering layer 8. The core 4 is preferably formedfrom a plurality of strands I0 of relatively strong material twistedtogether. Such strands 4 may be threads of cotton or like textilematerial, but it is preferred, for the sake of economy, to make them outof strong twisted paper. The individual strands of the two braidedcovering layers 6 and 8 are made of reinforced asbestos, each suchVstrand, shown at l2 in both Figures 1 and 2, having a centralreinforcing wire strand I4 and a covering layer I6 thereover of longbered asbestos. Although it is preferred to employ as the reinforcementfor the friction-disc of the invention the rope-like web 2 shown inFigure 2, having two braided covers thereon, because of the relativelylarger volume of voids and larger number of interstices therein, theremay be employed, as explained above, the web 2 shown in Figure 1 havinga single braided cover thereon. In the illustrations of Figures 3 to 8,inclusive, the web 2 shown in Figure 2 is shown as being used.

The rope-like web is cut into appropriate lengths so that each may bemade into the form of a one-turn coil, the resulting annuli or ringsfitting snugly one within the other. Preferably the webs are cut on abias, as shown .in Figurev 3, so that the abutting ends of each of theannuli I 8, 20, 22, 24, and 2.6 overlap each other somewhat, as shown at28, .30, 32, 34, and `36,

respectively. It is most convenient to accom-4 Y aseaeee clusive,between the abutting ends of the several annuli are staggered as shown,in approximately uniformly spaced angularl relationship. Y

The manner in which the armuu ls to 2a, inclusive, occupy the mold space38 and lie sideby-side when so assembled is most clearly shown in Figure4, which shows such annuli in the 'popositions they assumed afterassembly but before pressing. In Figure 5 is shown the disc resultingfrom such assembled 'annuli after they have been pressed by a male moldpart, not shown, having an annular portion interiit'ting with theannular recess 38 in the female mold part 4l). Such pressing operationcauses the p'rojecting portions on each of the annuli I8 to 26,inclusive, to be pressed into the confronting interstices in adjacentannuli, so that as a Vresult of such pressing operation there results auni'- tary self-sustaining disc 46, shown in Figure 5, such disc beingstrong enough to `withstand the subsequent processing step. Because theannuli at this stage are unimpregnated and thus soft, only moderatepressures are required in the above pressing operation.

Disc 46 is then impregnated with a bonding and friction treatmentmaterial. Such impregnation is most conveniently carried out byimmersing disc 46 in a bath of such material, a1- lowing it to remainuntil the bonding and friction-'treatment material has penetrated andfilled all or substantially all of the interstices in such'structure,and then removing the disc and allowing the bonding andfriction-treatment material to drain therefrom. Although it is to beAunderstood that various other known bondin'g and friction-treatmentmaterials may be employed for su'ch impregnation of the pressed disc, ithas 'been found that the following inaterial, given by way of exampleonly, produces admirable results:

Impre'gnating composition y The thermosetting resin may be, by way ofexample, a phenol-formaldehyde resin, of which that known as Durez 8045is typical.

The alcohol 'may be any one of the volatile lower alcohols acting asasolvent for resin. Or'- din'arily either methyl or ethyl alcohol ispreferred for this purpose.

Thedi'sc resulting from such irnpregnating step is shown at 48 'inFigure 6. After such step of impregnation, and after the volatilesolvent in the impregn'ant has evaporated to some extent, but while theimpregnant is still somewhat tacky, there is applied to the disc 48 afurther coating, shown at 5B on the disc, 'there-designated 52,illustrated in Figure '.7. Such further coating 58 consists largely'ofshort bered asbestos, mixed with `further bonding fandfriction-treatment material. Coating 5U may be applied to disc 48 by abrushing operation, or by spreading it on with a knife. By way ofillustration but'n'otlimitation, there is vgiven below a composition for4 coating 50 which has given very' satisfactory results. Frictiontreatment coating Percent by weight Short bered asbestos 70Thermosetting resin 17 Barytes 5 Hard rubber dust 5 Black iron o Xide(FesOi) sie; 1 2 Aluminum Steairatag 1 The thermosetting resin may be,by way of example, a phenol-formaldehyde resin, of which that vknown asDurez A8945 is typical.

After the solvent in coatingr 50 has evaporated so that such coating isthoroughly dry, the resulting coated disc, designated 52, is placed in amold having A a configuration similar to that shown fragmentarily inFigure 4, and is subjected to heat and pressure so as to cure and hardenthe impregnating bonding and friction treatment material and thematerial in coating 50, so that there results a very strong, hard,relatively inflexible disc. Such disc is then finished by being surfaceyground on one or both of its flat faces to produce the nnished `discshown in Figure 8. The disc there shown is `one which results from theuse of the double braid'- ed reinforcing rope-iike webs shown in Figure2, in which, .by reason'of-such double'braid covering, the volume of"the voids or interstices in. such web relative to the solid matter inthe web is large, and thus there is aiorded space for a high percentageby Weight of impregnant in disc 48. In the finished ground fface of thefriction-disc 52, shown in Figure 8, there will appear, on the surface,portions "of both the first 'and second br'aidedcoveri-n'g layers Gand 8of the rope-like webs, the interstices between such strands of thewebs'b'eing filled Awith'thecoating 50. The lighter area, in the portionoffthe disc shown in detail at the left in Figure 8, designates thestrands of the braided covering, and the darker areas designate theshrt-beid asbestos containing mix of coating '50. Thus, the strands inthe braided coverings appear as discontinuous elements inthefrictione'dis'c face, the wear o'n such face being `sustained 1l`a`1gi-ly by the remaining fragments of coating '530. Because ofthediscontiriuity in such face of fboth the strands in the braids, and ofthe shortfibered asbestos mix, the disc "face shows vlitt-leite'iideii5y 'tosmear 'and thus'to glaz'e. Y

-In the alternative method of making the fric'- tion-di's'cyindicated inFigures v49 and 1o, Vindividual annuli t8 :and 16, inclusive, are farmed`from a one-turn-cii 'ffaprriate eiametr made from therope-'likeweb 2.ach'such annulus, the ends of which may lb'eibuttedon'the bias, asinthe'eme bodiment shown in Figure 3, is pressed in an annular mold ofwhich a 'fragment `is shown in Figure `9, in which 54 A'designates "thefemale por-'- tion of the mold, and 56 the male -part thereof. Therecess 58 in-'inoldfpartf54 fhasfa straight inner shoulder60,"ahorizontal innerbottom surface 59, and an upwardly and outwardlyinclined'outer bottom surface 62. The `male ypart-56 is formed withYitsbottoin surfaceas shown, the outer por# tion 64 thereof beinghorizontal, vand the Vinner portion 66 beingfi'nclined'inwardly anddownwardly parallel to surface '62, Vso Vthat the space definedbetweenthe male and vfemale mold Vparts is `in cross '-sectioir a'rhoinbod.

The resultant annuliorfrings so treated, designated 68, '12, '14, *and16, respectively, are as= shape.A The inclined inner and outer edges ofthe inner annuli '10,- 12, and 14 snugly intert as shown, so that theupper and bottom faces of such annuli lie in planes. The inner and outerannuli 68 and '16, respectively, are provided with their inner facesinclined to intert, in a similar manner, with adjacent annuli, but theirradially outward and inward faces, respectively, are formed straight ina mold similar to that shown in Figure 9, except for the provision of amold recess of a shape such as to form` such modified shapes.

After the assembled disc has been pressed in the mold shown in Figurel0, in which 80 designates the male and 82 the female part thereof,there is produced a unitary self-sustaining disc quite similar to thatshown in Figure 5. Such disc may then be successively treated by thesteps of impregnation, partially drying the impregnant, and the furtherapplication of a bonding and friction-treatment coating such as coating5|] of the rst embodiment. Thereafter, the disc after drying of suchcoating, treated under heat and pressure to cure the impregnant, and thebonding and friction-treatment materials, and is then ground to producea nished disc, such as that shown in Figure 8.

Because of the fact that each of the reinforcing annuli formed from therope-like web is located in a circle coaxial of the disc, the structureof the disc, and thus its action in use is uniform throughout the areaof its friction face. The biasing of the joints between the ends of theannuli, and their being staggered about the disc as described, likewiseresult in a stronger, more uniform structure. The method of the presentinvention discloses marked advantages over those heretofore used, sinceall the pressing operations take place with the disc forming elementsand the disc itself in substantially dry condition. In the pressing ofthe annuli to form the disc, the ropelike webs are unimpregnated andthus, there is n o material which can stick to the mold parts or oozetherefrom. The pressing of the disc, after application of the coating 50thereto, is performed after such coating is thoroughly dry, and thushere again, there is no material such as resin, to stick to the moldparts or to escape therefrom.

Thus the cleaning and maintenance of the molds I employed in carryingout the method of the invention are nominal, and as a result, the methodis characterized by its economy of both labor and material.

Although I have described and illustrated preierred embodiments of thefriction-disc of the invention and of the method for making suchfriction-discs, it is to be understood that the invention is not limitedthereto, since it may be varied considerably as to details.

I claim as new the following:

1. The method of forming a generally at friction element comprising thefollowing steps in the order named: forming a series of similar hollowshapes of one closed turn of rope-like webs composed of a plurality ofelongated strands extending generally longitudinal of the web, theshapes being so related in size as to fit in progression one within theother and to lie generally in a plane, assembling such shapes in suchrecited manner to form a composite shape, compressing the thus assembledcomposite shape in a direction generally normal to its plane so thatthere results a unitary self-sustaining body, mpregfv nating such bodywith a heat hardenable fluid bonding and friction-treatment material,coating the thus impregnated body with a mix comprising a major amountof a comminuted filler and a minor amount of a heat hardenable binder, Y

allowing the thus coated body to dry, and curing the impregnatingmaterial and the binder in the coating by subjecting the body to heatwhile under pressure. l f

- 2. The method of forming a generally ilat friction element comprisingthe following steps ink the order named: forming -a series of similarhollow shapes of one closed turn of rope-like websV composed of aplurality of elongated strands extending generally longitudinal of theweb, each having exterior interlaced strands forming interstices andprojections, the shapes being so related in size as to t in progressionone snuglir within the other and to lie generally in a plane, y

assembling such shapes in such recited manner to form a composite shape,compressing the thus assembled composite shape in a direction normal toits plane so that there results a unitary selfsustaining body,impregnating such body with a heat hardenable fluid bonding andfriction-'treatment material, coating the thus impregnated body with amix comprising a major amount of a comminuted filler and a minor amountof a fluid heat hardenable binder, allowing the thus coated body to dry,and curing the impregnating material and the binder in the coating bysub-v jecting the body to heat while under pressure.

3. The method of forming a friction-disc comprising the following stepsin the order named: 'forming a series of rings of one closed turn ofrope-like webs composed of a plurality of elongated strands extendinggenerally longitudinal'of the web, each having exterior interlacedstrands forming interstices and projections, the rings being so relatedin size as to t in progression one snuglywithin the other and to liegenerally in a plane, assembling such shapes in such recited manner toform a composite disc, the abutting ends of successive rings beingstaggered angularly around the disc, compressing the thus assembledcomposite disc in a direction normal to its planeY so that thereVresults a unitary selfsustaining body, impregnating such body with aheat hardenable fluid bonding and friction-treatment material comprisinga synthetic resin, coating the thus impregnated body with a mixcomprising a major amount of a comminuted ller and a minor amount of aheat hardenable binder comprising a synthetic resin, allowing the thuscoated body to dry, and curing the impregnating material and the binderin the coating by subjecting the body to heat and pressure.

4. The method of forming a flat friction-disc comprising the followingsteps in the order named: forming a series of rings of one closed turnof rope-like Webs composed of a plurality of elongated strands extendinggenerally longitudinal of the web, each having exterior interlacedstrands forming interstices and projections, the abutting ends of eachring meeting on a bias, the rings being so related in size as to t inprogression one snugly within the other and to lie generally in a plane,assembling such shapes in such recited manner to form a composite disc,the abutting ends of successive rings being staggered angularly aroundthe disc, compressing the thus assembled composite disc in a directionnormal to its plane so that there results a unitary selfsustaining body,impregnating such body with a heaehardenabie aunabonding;enamoran-creata ment: material; composed largely of etsynthetic: resin coatings the; thus: impregnated body: with.amixeomprisine a maior;amount;offshortribered asbestos. and. a. minoramount. of.V a fluid; heel". htardenable4 binder comprising a synthetic.resihr, allowingl the. thus coated. body` to. dry.; and curp. ing theimpregnating materialA andthebnder the coating. by subjecting: the bodyto heat andi pressure.

5. Themethodof formingol generally'flatirictionelement. comprising thefollowingL stepsinf theordernamedzz. forming a seriesof similar hol.`low` shapes ofi one closedturn of rope-like4 Websy composed of.aplurality ofl elongated strands exa. tending. generally longitudinalofl the web each. havingexterior interlaeedstrands forming intera stces..andprojections, pressing` each such; Shape. individually.` tocompressit in. adillection normal toritsplane, theresulting shapes beingsorrelated in size as to, t4 snugly in. proeressionone within,

theother, assembling such shapesin such recited:`

manner to form a composite shape, compressing; the.y thus. assembled.composite. shape. in. a direc?.A tion normalto. its plane so that thereresultsa unitary self-sustainingv body,v impregnatingsuch; body withaheat. hardenahle fluid bonding and; frictionftreatment materiaLcoating. thethus im..- pregnated body. with amix comprising. a major.vamount. off` a comminuted llerr` and a. minor. amountofia.heat.hardenable binder, allowing. the'V thus; coated body to dry, andcuring the impregnatingmaterial and the binder in..the.coat-. ing" bysubjecting. the body to heatwhile under pressure.

6. The method of forming a.. flatfrictionfdisc comprising the followingsteps in. the order named: forming a series ofrings of oneclosed; turnofrope-like Webs composed of a plurality of:v elongated strandsextendinggenerally iongitudi-.l nal; of; the. web, each having exteriorinterlaced. strandsv forming interstices and; projections, the'.abutting ends of each ring meeting. on a bias,` pressing each such` ringindividually. tocompress it in a direction normal toits plane and-toshaper it with at least one. overhanging` edge, the result'- ingringsbeingso related insize and shape asito2 fitr-:snugly in progressionone Wit-hin: the.` other,l assembling' such shapes in such recited;manner-l 11o-form a composite disci the1 abutting; endsoi'. dv

successive rinesbeingzstaeeered:aneularly aros Y the.; onse,lcompressing: the thus. assembled com posite disoinl a direction.normal.- to its plane soy that.. resultaat. unitary.KA self-sustaining;loods; impreenatine.; such; loods! with a. heatv halidenahlea huidbondingI andI friction-treatment mate composed predominantly of; aSynthetic resin; @oat-inethef thus; impregnated bedr with. mir;oo.lrirzrirsingA a; maiorfamountof., shortY flberecli bestos.and;a;minorentier;aluidheathardrenablebioder.-comnrisinea Synthetic resinallowinathe thus coated body; to dry, and..v curing. the..impregnados-.materielandthe binder; in theorist ing by subjecting thebody to heat while under pressure..

7- The method oi' for-mine. a friction element. comprising.- theffollowing; steps in. the order:

named: forming a; series-of similar hollow shapes...` of: oneClosed-.turn of. rope-like websthe. shapes.

REFE.RENCES..l CITED The.y following referencesare of' record in the le.ofI this; patent:

Number Name Date 1,614,200 Kattwinkel Jan. 11,1927'- 2...025,03.9 Cannon1966. 2 4x, 1.935. 2,025,052 .HessY Deazaiosa 2.119,3 2.4. Wales. Mar.'7, 1939 2,196,569.y Stroehla et al. Apr. 9, 19411 2,240,358.

Walters Apr. 29.,A 139er

